Theorem falnanfal 1527

Description: A -/\ identity. (Contributed by Anthony Hart, 22-Oct-2010.) (Proof shortened by Andrew Salmon, 13-May-2011.)

Assertion

Ref	Expression
falnanfal	|- ( ( F. -/\ F. ) <-> T. )

Proof of Theorem falnanfal

Step	Hyp	Ref	Expression
1		nannot 1453	. 2 |- ( -. F. <-> ( F. -/\ F. ) )
2		notfal 1519	. 2 |- ( -. F. <-> T. )
3	1, 2	bitr3i 266	1 |- ( ( F. -/\ F. ) <-> T. )

Syntax hints:   -. wn 3   <-> wb 196   -/\ wnan 1447   T. wtru 1484   F. wfal 1488

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 197  df-an 386  df-nan 1448  df-tru 1486  df-fal 1489

This theorem is referenced by: (None)